lockd: Fix server-side lock blocking code

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 40 insertions, 33 deletions

diff --git a/fs/lockd/svclock.c b/fs/lockd/svclock.c
index d50946dcddd9..1d3a74df93f3 100644
--- a/fs/lockd/svclock.c
+++ b/fs/lockd/svclock.c
@@ -193,6 +193,7 @@ nlmsvc_create_block(struct svc_rqst *rqstp, struct nlm_file *file,
                 goto failed_free;
 
         /* Set notifier function for VFS, and init args */
+        block->b_call.a_args.lock.fl.fl_flags |= FL_SLEEP;
         block->b_call.a_args.lock.fl.fl_lmops = &nlmsvc_lock_operations;
         block->b_call.a_args.cookie = *cookie;  /* see above */
 
@@ -228,19 +229,18 @@ failed:
  * can be closed hereafter.
  */
 static int
-nlmsvc_delete_block(struct nlm_block *block, int unlock)
+nlmsvc_delete_block(struct nlm_block *block)
 {
         struct file_lock        *fl = &block->b_call.a_args.lock.fl;
         struct nlm_file         *file = block->b_file;
         struct nlm_block        **bp;
-        int status = 0;
+        int status;
 
         dprintk("lockd: deleting block %p...\n", block);
 
         /* Remove block from list */
         nlmsvc_remove_block(block);
-        if (unlock)
-                status = posix_unblock_lock(file->f_file, fl);
+        status = posix_unblock_lock(file->f_file, fl);
 
         /* If the block is in the middle of a GRANT callback,
          * don't kill it yet. */
@@ -282,7 +282,7 @@ nlmsvc_traverse_blocks(struct nlm_host *host, struct nlm_file *file, int action)
                         block->b_host->h_inuse = 1;
                 else if (action == NLM_ACT_UNLOCK) {
                         if (host == NULL || host == block->b_host)
-                                nlmsvc_delete_block(block, 1);
+                                nlmsvc_delete_block(block);
                 }
         }
         up(&file->f_sema);
@@ -297,7 +297,7 @@ u32
 nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
                         struct nlm_lock *lock, int wait, struct nlm_cookie *cookie)
 {
-        struct nlm_block        *block;
+        struct nlm_block        *block, *newblock = NULL;
         int                     error;
         u32                     ret;
 
@@ -310,59 +310,65 @@ nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
                                 wait);
 
 
-        /* Get existing block (in case client is busy-waiting) */
-        block = nlmsvc_lookup_block(file, lock, 0);
-
+        lock->fl.fl_flags &= ~FL_SLEEP;
 again:
         /* Lock file against concurrent access */
         down(&file->f_sema);
+        /* Get existing block (in case client is busy-waiting) */
+        block = nlmsvc_lookup_block(file, lock, 0);
+        if (block == NULL) {
+                if (newblock != NULL)
+                        lock = &newblock->b_call.a_args.lock.fl;
+        } else
+                lock = &block->b_call.a_args.lock.fl;
 
         error = posix_lock_file(file->f_file, &lock->fl);
+        lock->fl.fl_flags &= ~FL_SLEEP;
 
         dprintk("lockd: posix_lock_file returned %d\n", error);
 
-        if (error != -EAGAIN) {
-                if (block)
-                        nlmsvc_delete_block(block, 0);
-                up(&file->f_sema);
-
-                switch(-error) {
+        switch(error) {
                 case 0:
                         ret = nlm_granted;
                         goto out;
-                case EDEADLK:
+                case -EAGAIN:
+                        break;
+                case -EDEADLK:
                         ret = nlm_deadlock;
                         goto out;
                 default:                        /* includes ENOLCK */
                         ret = nlm_lck_denied_nolocks;
                         goto out;
-                }
         }
 
-        if (!wait) {
-                ret = nlm_lck_denied;
-                goto out_unlock;
-        }
+        ret = nlm_lck_denied;
+        if (!wait)
+                goto out;
+
+        ret = nlm_lck_blocked;
+        if (block != NULL)
+                goto out;
 
         /* If we don't have a block, create and initialize it. Then
          * retry because we may have slept in kmalloc. */
         /* We have to release f_sema as nlmsvc_create_block may try to
          * to claim it while doing host garbage collection */
-        if (block == NULL) {
+        if (newblock == NULL) {
                 up(&file->f_sema);
                 dprintk("lockd: blocking on this lock (allocating).\n");
-                if (!(block = nlmsvc_create_block(rqstp, file, lock, cookie)))
+                if (!(newblock = nlmsvc_create_block(rqstp, file, lock, cookie)))
                         return nlm_lck_denied_nolocks;
                 goto again;
         }
 
         /* Append to list of blocked */
-        nlmsvc_insert_block(block, NLM_NEVER);
+        nlmsvc_insert_block(newblock, NLM_NEVER);
+        newblock = NULL;
 
-        ret = nlm_lck_blocked;
-out_unlock:
-        up(&file->f_sema);
 out:
+        up(&file->f_sema);
+        if (newblock != NULL)
+                nlmsvc_delete_block(newblock);
         dprintk("lockd: nlmsvc_lock returned %u\n", ret);
         return ret;
 }
@@ -445,7 +451,7 @@ nlmsvc_cancel_blocked(struct nlm_file *file, struct nlm_lock *lock)
 
         down(&file->f_sema);
         if ((block = nlmsvc_lookup_block(file, lock, 1)) != NULL)
-                status = nlmsvc_delete_block(block, 1);
+                status = nlmsvc_delete_block(block);
         up(&file->f_sema);
         return status ? nlm_lck_denied : nlm_granted;
 }
@@ -519,7 +525,11 @@ nlmsvc_grant_blocked(struct nlm_block *block)
         }
 
         /* Try the lock operation again */
+        posix_unblock_lock(file->f_file, &lock->fl);
+        lock->fl.fl_flags |= FL_SLEEP;
         error = posix_lock_file(file->f_file, &lock->fl);
+        lock->fl.fl_flags &= ~FL_SLEEP;
+
         switch (error) {
         case 0:
                 break;
@@ -630,11 +640,8 @@ nlmsvc_grant_reply(struct svc_rqst *rqstp, struct nlm_cookie *cookie, u32 status
                 } else {
                         /* Lock is now held by client, or has been rejected.
                          * In both cases, the block should be removed. */
+                        nlmsvc_delete_block(block);
                         up(&file->f_sema);
-                        if (status == NLM_LCK_GRANTED)
-                                nlmsvc_delete_block(block, 0);
-                        else
-                                nlmsvc_delete_block(block, 1);
                 }
         }
         nlm_release_file(file);
@@ -661,7 +668,7 @@ nlmsvc_retry_blocked(void)
                 dprintk("nlmsvc_retry_blocked(%p, when=%ld, done=%d)\n",
                         block, block->b_when, block->b_done);
                 if (block->b_done)
-                        nlmsvc_delete_block(block, 0);
+                        nlmsvc_delete_block(block);
                 else
                         nlmsvc_grant_blocked(block);
         }